The High-Magnetic-Field Path To Practical Fusion Energy · 8/30/2017 High Field Path To Fusion 10...

The High-Magnetic-Field Path To Practical Fusion Energy

Presented by Martin Greenwald for MIT-PSFC TeamAugust 30, 2017

ARPA-E Annual Review – San Francisco

Acknowledgements

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Many contributions, particularly from

– ARC Team

– Dan Brunner

– Zach Hartwig

– Earl Marmar

– Joe Minervini & PSFC Magnet Group

– Bob Mumgaard

– Brandon Sorbom

– Dennis Whyte

Common Ground

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● Focus on mission, product, customer

● Need to move fast

● Centrality of Innovation

● Agile approach - Identify and retire risks at lowest cost

● Desire to raise the profile of fusion energy – place into the discussion of our energy future

Where we differ – technical approach

● MIT stresses robust and aggressive magnet engineering harnessed to proven physics

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The World Needs Reliable Carbon-Free Energy

Can Fusion Contribute To The Solution?

Dilemma - The Physics Is Mature, But… The Conventional Path Is Too Big, Too Slow

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2015 2020 2025 2030 2035 2040 2045 2050

$50 B $10 B ??$30 B ??

JETNow operating

JT-60SAUnder construction, 2019

ITER First plasma 2026

D-T 2035-2040

FNSF/Pilot (US)2040-2045 start?

DEMO (EU)2060 start?

First power on grid in >2070

Is There A Faster, Cheaper Way?

Before They Got Too Big, Tokamaks Demonstrated Enormous Progress

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Progress Exceeded Moore’s Law for 30 years

JT-60U (JP) KSTAR (KR)

NSTX-U (US) Tore Supra (FR)

HT-7 (CN)

MAST-U (UK)

COMPASS (CZ)

EAST (CN) JET (EU)DIII-D (US)

ASDEX-U (DE)Alcator C-Mod (US)

+ 170 other tokamaks across 60 yearsEnormous technical and scientific base

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● HTS technology has emerged into industrial maturity

● Form factor ideal for high-field fusion magnets

– Higher current densities

– Higher operating temperatures

– Strong (mostly steel) substrate

We Think The Basis For Breakthrough Is Here – High Temperature Superconductors

Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller

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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters

– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit

● Using “Standard” assumptions we can map out tokamak fusion performance

Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller

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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters

– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit

● Using “Standard” assumptions we can map out tokamak fusion performance

– Best LTS (Low Temperature Superconductor) is Nb3Sn; Large-volume fusion magnets can’t have much more than 5-6 T on axis

– Result: Machines are huge

Inaccessible with LTS Magnets

ITER

Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller

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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters

– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit

● Using “Standard” assumptions we can map out tokamak fusion performance

– Best LTS (Low Temperature Superconductor) is Nb3Sn; Large-volume fusion magnets can’t have much more than 5-6 T on axis

– Result: Machines are huge

● HTS ⇒ Double the field, cut the linear size in half. The volume, weight decrease by a factor of 8

ITER Fusion Pilot Plant Concept

ARC

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Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller

ARC9.2 T500 MW Fusion PowerWith same physics

ITER5.3 T500 MW Fusion Power

Increase B

ARC: Concept for Modular Fusion Pilot Plant

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●Originated in a Graduate design seminar at MIT

– Challenge was to use HTS to find the smallest machine that would produce 500 MW fusion power - using physics from existing experiments

– Reference: Sorbom et al., Fusion Engineering and Design 100, 378, 2015

●Not an engineering design, but

– Sufficient mechanical, hydraulic, nuclear and electrical calculations were performed to suggest engineering plausibility for this class of device

What’s The Basis For Our Confidence In This Path?

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1970 1980 1990 2000 2010 2020

Record Plasma Pressure (MFE)

High confidence in Tokamak physics performance

Record nτELawson number exceeded 1983

10cm

26T YBCO

C-Mod 8T Demountable magnet

12T Alcator C9T Alcator A

ITER Model CS

Levitated SC Coil

Twisted Stack HTS

First 10T SC Fusion Magnet

Invented CIC Superconductor Cable

High-Field Copper Magnets

<p> > 2 ATMn = 4×1020/m3

T = 5 keVτE = 0.1 sec

Alcator C-Mod, as a compact, high-field device performs as well in many metrics as devices up to 100x larger and more costly at the national and international scale

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JT60Japan3 Tesla

Alcator C-ModMIT

8 Tesla

JETEurope3 Tesla

Demonstrates the cost-effectiveness of the high-field approach

Innovations – Fast and Furious

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● HTS – High Field, Compact Size

– Cheaper, faster

– Modular – fabricate in factory, assemble on site

● Demountable Magnet

– Vastly improved fabrication & maintenance

● Immersion molten-salt blanket

– When core wears out – replace it

– Dramatically reduced solid radwaste (x50)

● Long-leg, x-point target divertor

– Fully detached operation

● High-field side LH current drive for sustainment

Upper halfOf TF

Lower halfOf TF(ToroidalField) coils

Vacuum vessel containing complex internals

Liquid blanket tank

When the core wears out, just replace it like fission.

Common Ground – Revisited

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To move ahead – issues we all face

● Regulation/licensing

● Siting

● Fuel Availability and Fuel Cycle

● Public perception/acceptance

● Zero-carbon incentives and tax credits

● Need for independent validation

– Safety

– Technical

– Economic

Moving Forward

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Now is the time

● Convene interested parties – build the required coalition

● Take the processes into our own hands

● Address common interests

– Private/Public relationship

– Begin to drive the regulatory process

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END

The narrative that high-performance tokamaks have to be big, & expensive in slow unwieldy programs is not true.

• There are some small very high performance early tokamaks

Alcator CMIT 197812 Tesla

Alcator AMIT 196910 Tesla

• These were enabled by a cutting edge technology at the time• High-field, cryogenically-cooled, high-strength copper

magnets developed for magnetic science (MRI, NMR, etc)• They were early, inexpensive, small, team-oriented, and quickly

constructed on a university campus• These, what might qualify as “startups”, beat the large devices

at the national labs to get the Lawson criteria above breakeven

Alcator C-Mod performs as well in many metrics as devices up to 100x larger and more costly at the national and international scale.

Approximately to scale

JT60Japan3 Tesla

Alcator C-ModMIT

8 Tesla

JETEurope3 Tesla

• It is well demonstrated that within tokamaks, high-performance can be achieved at small size

• Despite its size, C-Mod is a very high performance device• Operated in fusion-relevant regimes of plasma physics

(e.g. thermonuclear Te=Ti )• Contributes important data to the understanding of

tokamak operation

World-record tokamak pressure

7 keV

High D-D fusion yields

Alcator C-Mod achieves record breaking plasma performanceat small size and high field.